Is it poor form for a C# class to subscribe to its own published events?
c#, events
Solution
This sounds reasonable to me, but I can't help the nagging feeling that it's a poor practice, for the simple reason that I'm always faced with the question: "Why not perform the actions that you'd provide in the event handler in the code which fires the event?"
To answer that question, consider partial class scenarios. Suppose you have a base type B. You run an automated tool that decorates B by extending it to derived class D. Your tool generates a partial class so that developers consuming D can further customize it for their own purposes.
In that case, it seems perfectly reasonable that the user-authored side of D would want to sign up to be called when events declared by B or the machine-generated side of D are raised by the machine-generated side of D.
That was the scenario we found ourselves in when designing VSTO many years ago. As it turns out, it was not difficult to do this in C# but it was quite tricky to get it all working in VB. I believe VB has made some tweaks to their event subscription model to make this easier.
That said: if you can avoid this, I would. If you're just making an event for internal subscription that seems like a bad code smell. Partial methods in C# 3 help out greatly here, since they make it easy and low-cost for the machine-generated side to call little notification functions in the user-generated side, without having to go to the trouble of publishing an event.
Problem
I'm probably just being neurotic, but I regularly find myself in situations in which I have class that publishes an event, and I find it convenient to subscribe to this event from within the class itself (e.g. in the constructor), rather than only subscribing from external classes. This sounds reasonable to me, but I can't help the nagging feeling that it's a poor practice, for the simple reason that I'm always faced with the question: "Why not perform the actions that you'd provide in the event handler in the code which fires the event?" ``` public class Button { public Button() { this.Click += someHandler; // bad practice? } public event EventHandler Click; public void HandleInput() { if (someInputCondition) { // Perform necessary actions here rather than // subscribing in the constructor? this.Click(this, ...); } } } ``` Are there any drawbacks to subscribing to your own events?